Cultured human cells repair DNA damage induced by ultraviolet radiation and chemical mutagens and carcinogens. Little is known, however, about the fate of DNA-associated proteins (histones and non- histone nuclear proteins) during repair synthesis. An understanding of the metabolism of these proteins is of importance since rearrangements or derangements of their structure or function could lead to alterations in gene expression or activation with important cellular consequences. We have begun an investigation in this area by examining the rates of synthesis of histones and acidic nuclear proteins during repair synthesis.